The IRS has not given official guidance on how or if you will be able to change direct deposit information.
Please see these FAQ's about information from the IRS regarding anticipated economic impact payments:
How will the IRS know where to send my payment?
The vast majority of people do not need to take any action. The IRS will calculate and automatically send the economic impact payment to those eligible.
For people who have already filed their 2019 tax returns, the IRS will use this information to calculate the payment amount. For those who have not yet filed their return for 2019, the IRS will use information from their 2018 tax filing to calculate the payment. The economic impact payment will be deposited directly into the same banking account reflected on the return filed.
The IRS does not have my direct deposit information. What can I do?
In the coming weeks, Treasury plans to develop a web-based portal for individuals to provide their banking information to the IRS online, so that individuals can receive payments immediately as opposed to checks in the mail.
Please check back with these websites for updates regarding the ability to change your bank account information with the IRS.
I have changed banks since the first stimulus check. How do I update my account on Turbo Tax?
If you are asking about how to update your bank account to receive the second payment, the IRS did not make this possible to have the stimulus payment automatically sent to you. In all likelihood it will be necessary for you to claim the stimulus as additional refund on your 2020 tax return. Whether or not this is the case, you will be able to update your bank information as part of your 2020 tax return through the interview process.